Szechuanosaurus( "Szechuanlizard ") is an extinctgenusof carnivoroustheropoddinosaurfrom theLate Jurassic.Fossils referred to the genus have been found inChina,Asiain theOxfordian-?Tithonian(Penget al., 2005).[1]Itstype speciesis based on several undiagnostic teeth from theKuangyuan Series.[2][3]Additional possible specimens ofSzechuanosauruswere also reported from theKalaza Formation,[4]also located in China.
| Szechuanosaurus Temporal range:Late Jurassic,
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| Illustration of a partial tooth | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Neotheropoda |
| Genus: | †Szechuanosaurus Young,1942 |
| Type species | |
| †Szechuanosaurus campi Young, 1942
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Szechuanosaurusis at times regarded as anomen dubium[5][6]due to the lack of diagnostic features in the fossilized teeth upon which the genus is based.[7]Although the fossils are too fragmentary for confident identification,Szechuanosaurusis often interpreted as a medium-sizedallosaurid[8]or perhaps ametriacanthosaurid,[6]capable of reaching lengths of around 7.3 meters.[6]
Discovery and species
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Three species have been assigned to this genus over the years. Thetype speciesisSzechuanosaurus campi,named byYang Zhongjian( "Chung Chien Young" ) in 1942 for four isolated tooth specimens: IVPP V235, two partial teeth; IVPP V236, a partial tooth; IVPP V238, several tooth fragments; and IVPP V239, a single tooth. The teeth form asyntypeseries and were not found together. Also a very fragmentary skeleton, specimen UCMP 32102, was referred to the genus by Yang.[2]Some of the teeth indicate a large body-size. These fossils, although possiblymetriacanthosaurid,are now considered to be non-diagnostic, makingS. campianomen dubium.[9][10]The generic name refers to Szechuan. Thespecific namehonours the American paleontologistCharles Lewis Campwho had discovered UCMP 32102.[11]
A partial skeleton, CV 00214, was initially listed by Donget al.(1978) in a faunal list as a new species ofSzechuanosaurus,Szechuanosaurus yandonensis.[12]At first, there was no description or illustration of it, makingS. yandonensisat the time anomen nudum.Later,Dong Zhiminget alii(1983) described it, and assigned it toSzechuanosaurus campi[13]The affinities of this skeleton are uncertain, and it has only been briefly described. Holtzet al.(2004) included it in theirphylogenetic analysisand found it to be the mostbasaltetanuran.[14]This individual was a medium-sized theropod, with anischium(a pelvic bone) of 420 millimetres (17 in); for comparison, an ischium ofPiatnitzkysaurusestimated to weigh 504 kilograms (1,111 lb) is 423 millimetres (16.7 in) long.[10]In 2000,Daniel Churereferred the specimen to "Szechuanoraptordongi ", itself an invalidnomen ex dissertatione.[15]Carrano, Benson & Sampson (2012) synonymized it withYangchuanosaurusshangyouensisfrom the same formation.[16]
The third species isSzechuanosaurus zigongensis,named byGao Yuhuiin 1993 for an almost complete skeleton, specimen ZDM 9011.[17]It is an older species, from theMiddle Jurassic,appearing to be distinct from the type species and therefore requires its own genus name.[10]It was reassigned toYangchuanosaurus,as aYangchuanosaurus zigongensis,by Matthew Carrano, Roger Benson & Scott Sampson in 2012.[16]
Notes
edit- ^Peng, G.Z., Ye, Y., Gao, Y.H., Shu, C.K., Jiang, S. (2005):Jurassic dinosaur faunas in Zigong.Sichuan People’s Publishing House, 236 pp
- ^abYoung, C.C., 1942, "Fossil vertebrates from Kuangyuan, N. Szechuan, China",Bulletin of the Geological Society of China,22:293-309
- ^"Table 4.1," in Weishampel,et al.(2004). Page 78.
- ^"Table 13.1," in Weishampel,et al.(2004). Page 263.
- ^Sadleir, R. (2008).The Anatomy and Systematics of Eustreptospondyllus Oxoniensis, a Theropod Dinosaur from the Middle Jurassic of Oxfordshire, England.Palaentographical Society. p. 61.
- ^abcMolina-Pérez, Rubén; Larramendi, Asier; Connolly, David; Cruz, Gonzalo Ángel Ramírez (2019).Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes.Princeton University Press. p. 260.ISBN978-0-691-18031-1.
- ^Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004).The Dinosauria, Second Edition.University of California Press. p. 94.ISBN978-0-520-94143-4.
- ^Lucas, Spencer G. (2002).Chinese Fossil Vertebrates.Columbia University Press. pp. 141–142.ISBN978-0-231-50461-4.
- ^X.-C. Wu, P. J. Currie, Z. Dong, S. Pan, and T. Wang. 2009. A new theropod dinosaur from the Middle Jurassic of Lufeng, Yunnan, China. Acta Geologica Sinica 83(1):9-24
- ^abcBrusatte, S. L., Benson, R. B. J., and Xu, X. 2010. "The evolution of large-bodied theropod dinosaurs during the Mesozoic in Asia".Journal of Iberian Geology,36:275-296
- ^Camp, C.L., 1935, "Dinosaur remains from the Province of Szechuan",Bulletin of the Department of Geology of the Univiversity of California23:467-471
- ^Dong, Z., Chang, Li & Zhou, 1978, "Note on a new carnosaurYanchuangosaurus shangyuanensisgen. et sp. nov.) from the Jurassic of Yangchuan District, Szechuan Province ",Kexue Tongabao5:302-304
- ^Dong, Z-M., Zhou, S., Zhang, Y. (1983): [The dinosaurian remains of Sichuan Basin, China]. Palaeontologica Sinica (new series C), 23: 1–145 [in Chinese with English summary].
- ^Holtz, T.R., Molnar, R.E., Currie P.J. (2004): Basal Tetanurae. In: D.B. Weishampel, P. Dodson, P., H. Osmólska (ed.),The Dinosauria,2nd edn. University of California Press, Berkeley, 71-110
- ^Chure, D.J. (2000)A new species ofAllosaurusfrom the Morrison Formation of Dinosaur National Monument (UT–CO) and a revision of the theropod family Allosauridae.Unpublished Ph.D. dissertation, Columbia University, New York
- ^abCarrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)".Journal of Systematic Palaeontology.10(2): 211–300.doi:10.1080/14772019.2011.630927.S2CID85354215.
- ^Gao, Y., 1993, "A new species ofSzechuanosaurusfrom the Middle Jurassic of Dashanpu, Zigong, Sichuan ",Vertebrata PalAsiatica31(4): 308-314
